Cyclostationary Approach for Instabilities Detection and Condition Monitoring of Centrifugal Compressor

2020 ◽  
Author(s):  
Mateusz Stajuda ◽  
David Garcia Cava ◽  
Grzegorz Liśkiewicz
Keyword(s):  
Condition Monitoring ◽  
Centrifugal Compressor ◽  
Operating Conditions ◽  
Periodic Signal ◽  
Centrifugal Compressors ◽  
First Order ◽  
Standard Signal ◽  
Processing Techniques ◽  
Signal Processing Techniques ◽  
Insight Into

Abstract This study intends to explore the capabilities of the cyclostationary approach for instabilities detection and operating conditions monitoring of centrifugal compressors. Cyclostationary approach offers powerful signal analysis methods, applicable to different processes. It was proven useful for analysis of vibration, acoustic and pressure data for systems exhibiting periodicity. Cyclostationarity has been used for extracting subtle changes between cycles of the periodic signal which could be used for condition monitoring. Recent research focuses on employing this method for fault indication. Cyclostationary approach has not been extensively used in the field of turbomachinery, except for a few cases when it was proven to give a better insight into flow structure than standard signal processing techniques and allow for the detection of instabilities in flow systems. Thus, the cyclostationary approach may be suitable for instabilities detection and condition monitoring in centrifugal compressors. This paper exploits various techniques employing a cyclostationary framework for instabilities detection and operating conditions monitoring with the use of pressure signals from the low-speed centrifugal compressor. The most prospective cyclostationarity-based indicators are applied for the detection of instabilities. Due to a lack of second-order cyclostationarity, the study confines to the analysis of first-order cyclostationarity strongly exhibited in the compressor pressure signal. First-order cyclostationarity analysis provides an indication of instabilities and working conditions differentiation, but due to time-domain sampling, it is not fully robust and reliable. The highest potential is perceived in the cyclostationary approach use to extract changes between cycles. Different measures of change in variability could serve as a valuable indicator of instabilities.

Multistage Centrifugal Compressor Surge Analysis: Part I — Experimental Investigation

1998 ◽  
Author(s):  
G. L. Arnulfi ◽  
P. Giannattasio ◽  
C. Giusto ◽  
A. F. Massardo ◽  
D. Micheli ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Centrifugal Compressor ◽  
Reference Data ◽  
Dynamic Control ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Multi Stage ◽  
Compressor Surge ◽  
Multistage Centrifugal Compressor ◽  
Insight Into

This paper reports an experimental investigation on centrifugal compressor surge. The compression system consists of a four-stage blower with vaned diffusers and a large plenum discharging into the atmosphere through a throttle valve. Measurements of unsteady pressure and flow rate in the plant, and of instantaneous velocity in the diffusers of the first and fourth compressor stage are performed during deep surge, at several valve settings and three different rotation speeds. Additional tests have been carried out on a different system configuration, i.e., without plenum, in order to obtain the steady-state compressor characteristics and to collect reference data on stall in surge-free conditions. In this configuration, a fully developed rotating stall was detected in the compressor diffusers, while during surge it affects only a limited part of the surge cycle. The goal of the present experimental work was to get a deeper insight into unstable operating conditions of multi-stage centrifugal compressors and to validate a theoretical model of the system instability to be used for the design of dynamic control systems.

Data-Driven Predesign Tool for Small-Scale Centrifugal Compressor in Refrigeration

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Mounier Violette ◽  
Picard Cyril ◽  
Schiffmann Jürg
Keyword(s):  
Centrifugal Compressor ◽  
High Efficiency ◽  
Design Procedure ◽  
Integrated System ◽  
Operating Conditions ◽  
Data Driven ◽  
Small Scale ◽  
Centrifugal Compressors ◽  
Starting Point ◽  
Isentropic Efficiency

Domestic scale heat pumps and air conditioners are mainly driven by volumetric compressors. Yet the use of reduced scale centrifugal compressors is reconsidered due to their high efficiency and power density. The design procedure of centrifugal compressors starts with predesign tools based on the Cordier line. However, the optimality of the obtained predesign, which is the starting point of a complex and iterative process, is not guaranteed, especially for small-scale compressors operating with refrigerants. This paper proposes a data-driven predesign tool tailored for small-scale centrifugal compressors used in refrigeration applications. The predesign model is generated using an experimentally validated one-dimensional (1D) code which evaluates the compressor performance as a function of its detailed geometry and operating conditions. Using a symbolic regression tool, a reduced order model that predicts the performance of a given compressor geometry has been built. The proposed predesign model offers an alternative to the existing tools by providing a higher level of detail and flexibility. Particularly, the model includes the effect of the pressure ratio, the blade height ratio, and the shroud to tip radius ratio. The analysis of the centrifugal compressor losses allows identifying the underlying phenomena that shape the new isentropic efficiency contours. Compared to the validated 1D code, the new predesign model yields deviations below 4% on the isentropic efficiency, while running 1500 times faster. The new predesign model is, therefore, of significant interest when the compressor is part of an integrated system design process.

CHARACTERIZATION OF STOCHASTIC PROPAGATION AND SCATTERING VIA GABOR AND WAVELET TRANSFORMS

1994 ◽  
Vol 02 (03) ◽  
pp. 345-369 ◽  
Author(s):  
L. H. SIBUL ◽  
L. G. WEISS ◽  
T. L. DIXON
Keyword(s):  
Wavelet Transforms ◽  
Acoustic Scattering ◽  
Time Intervals ◽  
First Order ◽  
Spreading Function ◽  
Time Variations ◽  
Processing Techniques ◽  
Signal Processing Techniques ◽  
Methods Numerical

An application to remote acoustic sensing that remains unexploited is measuring acoustic scattering and spreading effects with wideband, coherent signal processing techniques. Such techniques allow distributed objects, such as a layer of scatterers due to bubbles or biological particles, and first order time variations in an ocean channel to be estimated. This paper presents narrowband and wideband methods for characterizing stochastic propagation and acoustic scattering in a time-varying ocean in terms of spreading functions. It is shown that the Gabor transform is the natural transform for estimating the narrowband spreading function, and the wavelet transform is the natural transform for estimating the wideband spreading function. Both techniques of characterization use a correlator processing structure in a monostatic transmitter/receiver configuration to estimate the spreading function. The narrowband and wideband spreading functions characterize the distribution of scatterers in range and velocity (time and frequency) in a propagation channel. It is shown that the wideband formulation follows directly from a physical derivation. Moreover, wideband processing removes many of the narrowband restrictions and allows first order time variations, caused by inhomogeneities and relative motion in the ocean channel, to be processed. In addition, wideband techniques allow for increased time intervals and, therefore, increased energy transmission when the transmitter is peak-power-limited. Thus, weak scatterers that may have been unidentified with narrowband techniques may be identified with the wideband methods. Numerical examples for wideband characterization of a distributed scatterer are presented.

scholarly journals Effect of Vaneless Diffuser Shape on Performance of Centrifugal Compressor

2020 ◽  
Vol 10 (6) ◽  
pp. 1936
Author(s):  
Qian Zhang ◽  
Qiuhong Huo ◽  
Lei Zhang ◽  
Lei Song ◽  
Jianmeng Yang
Keyword(s):  
Numerical Simulation ◽  
Energy Loss ◽  
Pressure Distribution ◽  
Centrifugal Compressor ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Vaneless Diffuser ◽  
Centrifugal Compressors ◽  
Parallel Wall

The influence of four different vaneless diffuser shapes on the performance of centrifugal compressors is numerically studied in this paper. One of the studied shapes was a parallel wall diffuser. Two others had the width reduced only from hub and shroud and the rest had the width reduced from hub and shroud divided evenly. Then the numerical simulation was employed and the overall compressor aerodynamic performance was studied. The detailed velocity and pressure distribution and energy loss within the centrifugal compressor with different diffuser geometries and different operating conditions were analyzed. The results revealed that shroud pinch significantly improved the overall compressor aerodynamic performance more than any other pinch types, and the best performance can be achieved by pinched diffusers under the design condition compared with pinched diffusers under the near surge condition or choking condition. The range of energy loss, namely the static entropy area in the compressor, become reduced with the above three pinches diffusers.

scholarly journals Gearbox Fault Diagnosis Based on Vibration Signals Measured Remotely

2009 ◽  
Vol 413-414 ◽  
pp. 175-180 ◽  
Author(s):  
Salem Al-Arbi ◽  
Feng Shou Gu ◽  
Lu Yang Guan ◽  
Andrew Ball ◽  
Abdelhamid Naid
Keyword(s):  
Signal Processing ◽  
Fault Diagnosis ◽  
Condition Monitoring ◽  
Transmission System ◽  
Gear Transmission ◽  
Gear System ◽  
Vibration Signals ◽  
Remote Measurements ◽  
Processing Techniques ◽  
Signal Processing Techniques

In many cases, it is impractical to measure the vibrations directly at or close to their source. It is a common practice to measure the vibration at a location far from the source for condition monitoring purposes. The vibration measured in this way inevitably has high distortions from the vibrations due to the effect of the attenuation of signal paths and the interference from other sources. The suppression of the distortions is a key issue for the remote measurements based condition monitoring. In this paper, the influences of transducer locations are investigated on a typical gearbox transmission system for the detection of the faults induced to the gearbox. Several signal processing techniques’ analysis results show that the attenuation and interference cause high influences on the gear transmission signals. However, time synchronous average (TSA) is very effective to detect the local faults induced to the gear system.

Multistage Centrifugal Compressor Surge Analysis: Part I—Experimental Investigation

1999 ◽  
Vol 121 (2) ◽  
pp. 305-311 ◽  
Author(s):  
G. L. Arnulfi ◽  
P. Giannattasio ◽  
C. Giusto ◽  
A. F. Massardo ◽  
D. Micheli ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Control Systems ◽  
Centrifugal Compressor ◽  
Reference Data ◽  
Dynamic Control ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Compressor Surge ◽  
Multistage Centrifugal Compressor ◽  
Insight Into

This paper reports an experimental investigation on centrifugal compressor surge. The compression system consists of a four-stage blower with vaned diffusers and a large plenum discharging into the atmosphere through a throttle valve. Measurements of unsteady pressure and flow rate in the plant, and of instantaneous velocity in the diffusers of the first and fourth compressor stage, are performed during deep surge, at several valve settings and three different rotation speeds. Additional tests have been carried out on a different system configuration, i.e., without plenum, in order to obtain the steady-state compressor characteristics and to collect reference data on stall in surge-free conditions. In this configuration, a fully developed rotating stall was detected in the compressor diffusers, while during surge it affects only a limited part of the surge cycle. The goal of the present experimental work was to get a deeper insight into unstable operating conditions of multistage centrifugal compressors and to validate a theoretical model of the system instability to be used for the design of dynamic control systems.

Paper 5: The Development of Centrifugal Gas Compressors for Process Plant Duty

1969 ◽  
Vol 184 (18) ◽  
pp. 45-53
Author(s):  
H. F. Ibbott
Keyword(s):  
Detailed Analysis ◽  
Centrifugal Compressor ◽  
Operating Conditions ◽  
Design Features ◽  
Centrifugal Compressors ◽  
Compressor Rotor ◽  
Process Plant ◽  
Full Speed ◽  
Process Plants ◽  
Gas Seals

This paper describes the various types of centrifugal compressor used in process plants, and continues to discuss the more important components of these compressors and particular design features which are required to overcome some difficult operational problems. Items of particular interest include a discussion on the latest form of compressor rotor construction, the techniques required for balancing a rotor at full speed, and a detailed analysis of shaft gas seals and problems that can arise with gas seals under certain operating conditions. The paper also describes such special subjects related to process plant compressors as compressor selection and design by utilization of computers, methods of reducing time to produce compressor orders by discrete stockholdings; types of driver and shaft couplings used for these machines, and test facilities employed for centrifugal compressors which can be utilized to reduce commissioning periods at site.

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